Clamp for splicing machines



Nov. 22, 1955 A. B. CLAYTON ETAL.

CLAMP FOR SPLICING MACHINES Filed April 8, 1953 W 35 p t IT #4 r w. n!

IHH' T ll u Hul Th 11v 3| 22 [I M II M Sheets-Sheet 1 INVENTOR.

ALFRED B. CLAYTON BY ALFRED N. IKNAYAN ATTORNEY.

V- 22, 1955 A. B. CLAYTON ETAL 2,724,424

CLAMP FOR SPLICING MACHINES Filed April 8, 1953 3 Sheets-$heet 2 IN VENTOR. ALFRED B. CLAYTO'N y AL FRED N. IKNAYAN E 4 92m W/Zw' ATTORNEY.

Nov 22. 1955 A. B. CLAYTON ETAL 2,724,424

CLAMPFOR SPLICING MACHINES Filed April 8, 1953 3 Sheets-Sheet 3 1N]'l-IN TOR. ALFRED B. CLAYTON By ALFRED N. IKNAYAN ATTORNEY.

2,724,424 Patented Nov. 22, 1 955 2,724,424 CLAMP FoR SVPLTCING MACHINESApplication April 8, 1953, Serial No. 347,502

Claims. 01. 154-9 This invention relates to clamps for use on trimmingand splicing machines for clamping in flattened condition the endportions of tubular stock so that the ends may be trimmed and buttspliced together to form an article such as for example, an inner tube.

The most common type of clamps heretofore used for this purposeconsisted of two fiat jaws between which the tube stock was clamped.There are, however, certain United States Patent Ofifice made up of aplurality of self-adjusting laminae, as each laminae of the jaw forms ashear mark on the tube.

3 The primary object, therefore, of the present invention is to'providea clamp having opposed clamping jaws of a novel contour which willengage and apply positive pressure across the full width of the tubestock without crushing or creasing the folded lateral edges of theflattened tube stock so that the ends of the stock may be extruded orbulged outwardly uniformly across the full width of the stock whenadditional pressure is applied to the clampingjaws and so that, thebulged. ends of the stock adjacent the lateral edges will not slip backin between the jaws when the ends are forced together in abuttingengagement to form a splice.

Other objects and advantages of the present invention will becomeapparent from the following description objections to using this type ofclamp particularly for heavy service type inner tubes. When the ends ofthe tubular stock are clamped between the flat jaws of this type ofclamp, the folded lateral edges of the stock are severely crushed andpermanently creased with the result that the tube stock is permanentlydeformed in this region. This deformation often results in cracks on theexterior surface of the tube along the folded edge and also cracks in,the interior surface of the tube along the fold when the tube isinflated and cured. This latter cracking is commonly knowns as foldbreakdown. This cracking of the tubes necessarily results incomparatively weak tubes and if the cracking is severe, the tubes mustbe discarded.

Attempts have been made to eliminate this crushing and creasing of therounded, folded edges of the tube stock by making the lower jaw ofchannel shape and providing undercut recesses in the sidewalls thereofinto which the lateral edges of the stock can be inserted. The upper jawcontacts only that portion of the tube extending between the sidewallsand does not contact the folded lateral edges which are inserted in therecesses. Clamps of this structure are shown in U. S. Patent No.2,145,607 to Nichols. The objection to this type of clamp is thatsubstantially no pressure is applied to the lateral folded edges of thetube stock and when the clamped ends are trimmed and moved into abuttingengagement to form asplice, the lateral edges being unrestrained by theclamping jaws tend to be pushed back into the recesses and the resultingsplice is very weak adjacent the lateral edges. When it is attempted toform a rindless splice according to the method described. in U. S.Patent No. 2,550,566 to Iknayan and Clayton, in which the stock isbulged or extruded out from the faces of the clamps by increasing thepressure between the clamping jaws, the portion of the tube adjacent tothe lateral edges being substantially unaffected by increasing thepressure between the clamps do not bulgeoutwardly to any substantialdegree and the resulting spliceformed by abutting the bulged outportions together is therefore very weak at the lateral edges of thetube. In addition, the engagement of the upper jaw with the tube sectionbetween the lateral edges of the tube rather than across the full widthof the tube result in shear marks being formed on the surface of thetube alongthe edges of the top jaw. In some instances, the top jaw mayactually cut into the tube. This latter objection also applies to. theuse of a laminated clamp of the type shown in U. S. Patent No. 2,040,466to Christy in which one jaw is when read in conjunction with theaccompanying drawings wherein:

Fig. 1 is a perspective view of a set of clamping jaws forming oneembodiment of the clamp of the present invention;

Fig. 2 is a partial elevational view of a tube trimming and splicingmachine incorporating the clamp structure of Fig. l;

Fig. 3 is a side elevation taken along the line lII-III of Fig. 2showing the clamping jaws retracted and a piece of tube stock in placeon the lower jaw;

Fig. 4 is a side elevation similar to that shown in Fig. 3 but showingthe jaws clamping the end of the tube stock;

Fig. 5' is an enlarged partial sectional view showing the details of thecontour of the two clamping jaws in clamping position;

Fig. 6 is a plan view of the two clamps of the machine of Fig. 2 showinghow the ends of the tubes are extruded or bulged out uniformly acrossthe full width thereof when the pressure on the clamps is increasedafter the ends have been trimmed;

Fig. 7 is a sectional view taken on the line VII-VII of Fig. 6 showingthe extruded or bulged out ends of the tube stock preparatory to theirbeing forced together to form a splice; j

Fig. 8 is a sectional view of a slightly modified form of the clamp ofthe invention; and v j Fig. 9 is a sectional view of still anothermodification of the clamp of the invention.

Referring to the drawings and in particular to Fig. 1 of the drawings,the clamp of the present invention includes an upper jaw 10 and a lowerjaw 11 between which the end of a section of flattened inner tube stockmay be clamped. As will hereinafter be described in detail, the clampingsurfaces of the jaws 10 and 11' are specially contoured so that the tubestock is firmly gripped across the full width thereof without crushingor creasing the lateral folded edges thereof. 1 s

As shown in Fig. 2, the jaws10 and 11 are intended to be used on innertube trimming and splicing machines for separately clamping the endportions of a section of uncured inner tube stock T so that the endsmaybe trimmed and butt spliced together to form an inner tube. Theparticular machine shown in Fig. 2, is of the "type disclosed in U. S.Patent No. 2,576,940, but it is to be in U. S. Patent No. 2,576,940. Theupper jaws 10 are moved towards the lower jaws 11 to separately clampthe end portions of the inner tube stock T therebetween in opposedrelationship by admission of fiuid under pressure to cylinders 15 and16. The ends of the stock T protruding from the opposed faces of thejaws are trimmed by knives 17 and '18 and the trimmed ends are buttspliced together by admission of fluid under pressure to a cylinder 19which moves the carriages .13 and 14 toward each other.

Referring again to Fig. .1, the lower jaw 11 has a channel shape recess.20 formed therein. The width of the recess 20 is substantially equal tothe width of the particular tube stock T to be clamped. The upper jaw isof substantially the same width as the recess 20 so that it may beslidably received therein between the vertical sidewalls 21 and 22thereof to clamp the end of the section of inner tube stock '1 betweenthe under clamping face 23 of the upper jaw 10 and the base surface 24of the recess 20 of the lower jaw 11.

' The upper jaw 10 is secured by welding to a backing plate 25. Thebacking plate .25 extends beyond each sideof the jaw 10 and isbifurcated at each end to pro vide' rectangular slots 26 which receiverectangular guide posts 27. The guide posts 27 are secured to andextendvertically upwardly from the lower jaw 11 adjacent each side of therecess 20. The slots 26 and the guide posts 27 cooperate to insureproper alignment of the upper jaw 10 and the lower jaw 11 when the jawsare moved together to clamp the inner tube stock T.

The backing plate 24 is provided with an opening 28 for receiving apivot pin 29 so that it may be pivotally attached to the movable platen30 of the trimming and splicing machine in the manner described in U. S.Patent No. 2,576,940. The upper edges of the channel shape recess 20 ofthe lower jaw 11 are charnfered as indicated at 31 to facilitate thereception of the upper jaw 10 between the sidewalls 21 and 22.

The base surface 24 of the recess 20 is joined to the perpendicularlyextending sidewalls 21 and 22 by smooth, tangential, concave, filletsurfaces 32. The radius of curvature of the surfaces 32 is substantiallyequal to the radius of the folded lateral edges L of the tube stock T sothat the edges of the stock will not be deformed when clamped betweenthejaws 10 and 11. The under clamping face 23 of the upper jaw 10 isformed by two con-. cave grooves 33 which extend along the oppositelateral edges thereof and a flat surface 34 which joins the two grooves33. The juncture of the grooves 33 and the surface 34 is carefullyrounded to eliminate sharp edges. The radii of the grooves 33 areapproximately equal to that of the folded lateral edges L of the tubestock T to be clamped. The depth of the grooves are made substantiallyless than the thickness of the folded lateral edges L of the tube stock'T, but are of suflicient depth to prevent crushing or creasing of thefolded lateral edges L of the stock 'T when the stock is clamped, sothat the stock 'T will be firmly gripped but the lateral folded edges Lnot be severely crushed or creased. Good results have been obtained ifthe depth of the grooves 33 is held to between and percent, of theaverage wall thickness of'the uncompressed tube stock T at or near thelateral edge L. i

The intersections of the grooves 33 with the sides 35 of the upper jaw10 form comparatively sharp edges 36, thereby insuring that there are nosurfaces when the jaws 10' and llare moved together between which thelateral edges L of the tube stock T might be pinchedor crushed andinsuring that the lateral edges L of the tube stock Twill be containedwholly within the space formed by the fillet surfaces 32 and the grooves33.

Referring to Figs. 2 and 3, the ends of the inner tube stock. T arefirst laid in the channel shape recesses 20 of the lower jaws l1 andfluid under pressure is then admitted to the cylinders 15 and 16 to movethe platens and the upper jaws 10 attached thereto towards the lowerjaws 11 to clamp theinner tube stock as shownin Fig. 4. Alignmentoffthe'jaws is insured by engagement of the guide posts27 in the slots26. As best shown in the enlarged partial sectional view-of Fig. 5. thefolded lateral edges L of the tube stock T occupy the spaces formedbetween the grooves '33 and the fillet surfaces 32 so that whilepressure is exerted on the lateral edges L, the pressure is not sosevere as to crush or crease the edges L and therefore cause cracking.By this construction, the pressure exerted by clamps 10 and 11 on thetube stock T is substantially uniform across the full width of the tubestock T and when the pressure is increased to bulge or extrude out theends of the stock as shown in Fig. 7 in accordance with the methoddescribed in U. S. Patent No. 2,550,566, the bulging or extrusion of thetrimmed ends will be substantially uniform across the full width of thestock T as shown in Fig. 6. Being firmly gripped across the full width,there is no chance of the stock slipping back between the jaws whenthebulged ends are forced together to form a splice. Accordingly thesplice is uniformly strong across the full width thereof and no Weakspots are developed.

In Fig. 8, there is shown a slightly modified form of the invention. Inthis modification, grooves 33a are provided along the lateral edges ofthe recess 20a of the lower jaw 11a. The upper jaw 10a is provided witha flat surface 34a which terminates at opposite edges in concavesurfaces 32a which form comparatively sharp edges 36a with the sides aof the jaw 10a. It will be noted that the resulting spaces formedbetween the grooves 33a and the surfaces 32a are similar to those formedbetween the grooves 33 and the fillet surfaces '32 of the embodimentshown in Fig. 1. The depth of the grooves 33a are'similarly proportionedwith respect to the tube stock T to be clamped as the grooves 31 andthey function in the same manner to prevent crushing or creas l ing ofthe lateral edges .L of the tube stop T.

In Fig. 9, there is shown still another modification.

This modification in effect is a combination of those shown in Fig. 1and Fig. 8 in that grooves 33b are provided in the upper jaw 10b andgrooves 33c are provided in the lower jaw 11b. The individual grooves33b and 330 are, however, substantially shallower than the grooves 33 ofFig. 1 or the grooves 331: of Fig. 8, inasmuch as the combined depth ofgrooves 33b and 33c are substantially equal to the depth of grooves 31of Fig. 1. When the jaws 10b and 11b are moved together the grooves 33band 330 form spaces which accommodate the lateral edges L of the tubestock T and thereby prevent severe crushing or creasing thereof Whileallowing the tube to be firmly gripped.

From the above description, it can be seen that there is provided anovel clamp structure for use in inner tube trimming and splicingmachines. The clamp structure is characterized by the novel contour ofthe clamping jaws which permits the inner tube stock to be firmly anduni" formly gripped across the full width of the tube stock Withoutcrushing or creasing the folded lateral edges of the stock, therebyreducing cracking or'fold breakdown. This novel contour of the clampingjaws permits the application of uniform pressure across the full widthof the stock so that the ends can be uniformly bulged or extruded fromthe opposed faces of the jaws in accordance with the method described inU. S. Patent No. 2,550,566 and so that the bulged ends may be forcedinto butting engagement to form a splice without danger of the portionsthereof adjacent the lateral edges slipping back inv between the jaws.This uniform clamping of the stock also insures better and more uniformcutting or trimming of the ends of the stock preparatory to forming thesplice. The smooth contour of the jaws of the clamps insure that noshear marks will be formed on the tubes.

It is to be understood that the above description and the drawings arefor the purpose of illustration only and not by the way of limitationand changes in modification may be made. therein without departing fromthe spirit and scope of the invention.

l. A clamp for clamping tubular stock in flattened con dition,comprising a pair of opposed clamping jaws providing flat opposedparallel clamping surfaces of substantially the same width between whichthe flattened tube stock is adapted to be clamped, the clamping surfaceof at least one of said jaws having inwardly curved, parallel concavegrooves formed therein along opposite lateral edges thereof toaccommodate the folded lateral edges of the tube, and means for movingsaid jaws toward and away from each other to clamp said, flattened tubebetween said clamping surfaces.

2. A clamp for clamping tubularstock in flattened condition, comprising,a pair of opposed clamping jaws providing flat opposedparallel clampingsurfaces of substantially the same width between which the flattenedtube stock is adapted to be clamped, parallel sidewalls extendingperpendicularly from the clamping surface of one of said jaws atopposite lateral edges thereof between which the other of said clampingjaws is adapted to be slidably received, the clamping surfaces ofatleast one of said jaws having inwardly curved, concave, grooves formedtherein along each of its opposite lateral edges parallel to saidsidewalls.

3. A clamp for clamping tubular stock in flattened condition comprising,a pair of opposed clamping jaws, one of said jaws having achanneled-shaped recess therein, said channeled-shaped recess having aflat base providing a flat clamping surface and perpendicularlyextending flat parallel sidewalls, said otherjaw being of a widthsubstantially equal to the width of said channeled-shaped recess andadapted to be slidably received in said recess between said sidewalls,said other jaw being provided with a flat clamping surface parallel tothe clamping surface of said one jaw, the clamping surface of at leastone of said jaws being provided with an inwardly curved, concave, groovealong each of its lateral edges parallel to said sidewalls toaccommodate the folded lateral edges of said flattened tube stock.

4. A clamp for clamping tubular stock in flattened condition comprising,a pair of opposed clamping jaws providing opposed parallel clampingsurfaces of substantially the same width, each of said clamping surfacescomprising two laterally spaced, inwardly curved, concaved groovesconnected together by a flat surface, said grooves serving toaccommodate the lateral folded edges of said tube, and means for movingsaid jaws together to clamp said flattened tube stock between saidclamping surfaces.

5. A clamp for clamping tubular stock in flattened condition comprising,a pair of opposed clamping jaws, one of said jaws having achanneled-shaped recess therein, said channel-shaped recess having afiat base providing a clamping surface and perpendicularly extendingflat parallel sidewalls, said flat base and sidewalls being connectedtogether by smooth, concave, fillet surfaces, said other jaw being of awidth substantially equal to the width of said recess and adapted to beslidably received between said sidewalls, said other jaw being providedwith a clamping surface comprising two inwardly curved, concave groovesextending along two opposite marginal edges of the jaw parallel to saidsidewalls interconnected by a flat surface, the depth of saidgroovesbeing less than the thickness of the folded lateral edge of the tubestock.

References Cited in the file of this patent UNITED STATES PATENTS1,358,957 Ielley et al. Nov. 16, 1920 1,610,286 Hood et al. Dec. 14,1926 2,273,464 Campbell et al Feb. 17, 1942 2,312,333 Gramelspacher Mar.2, 1943 2,550,566 Iknayan et al. Apr. 24, 1 951 2,556,305 Vickers June12, 1951 OTHER REFERENCES Esso Laboratories, Splicing Problems in theManufacture of Butyl Inner Tubes, pp. 6 and 9.

